1. Field of the Invention
The invention relates to a sole structure, more particularly to an orthopedic sole structure which is adapted to be disposed in a shoe in order to cushion a foot and which is capable of relieving foot problems.
2. Description of the Related Art
A human foot is supported by a bone structure which is made up of a metatarsals portion, a tarsals portion an intermediate arch portion interposed therebetween such that the load of the body is concentrated on the bone structure of the foot. The intermediate arch portion is substantially curved upward with respect to the metatarsals and tarsals portions, thereby forming an inwardly bent portion and consequently resulting in a void under the intermediate portion of the sole of the foot. When a foot is disposed in a shoe, most of the weight is distributed on the metatarsals and tarsals portions that rest on the sole of the shoe. In case the intermediate portion of the sole of the human foot adjacent to an inner lateral side thereof cannot form a void relative to the metatarsals and tarsals portion of the foot, discomfort and pain at the sole of the foot will be aggravated when wearing a shoe.
Referring to FIG. 1, a bottom view of a conventional orthopedic sole structure for use in a shoe is shown to include an insole 10 and a cushion pad 13. The insole 10 includes a metatarsals support portion 11, a tarsals support portion 12 and an intermediate arch support portion 14 interposed therebetween. The cushion pad 13 is disposed at the intermediate arch support portion 14 of the insole 10. When a foot is disposed in a shoe provided with the aforesaid conventional orthopedic sole structure, the intermediate arch support portion 13 of the latter permits resting of the intermediate arch portion of the foot thereon, thereby relieving pain attributed to flattening of the intermediate arch portion of the foot.
It is noted that in the aforesaid conventional orthopedic sole structure, the metatarsals, tarsals and intermediate arch support portions 11,12, 14 and the cushion pad 13 are made from the same polymeric material. As such, the cushion pad 13 and the intermediate arch support portion 14 easily deform and are liable to get thinner due to weight concentration thereon and after a long period of use, thereby affecting adversely the pain relieving effect.
The object of this invention is to provide an orthopedic sole structure for use in a shoe so as to cushion the sole of a foot in order to overcome the aforesaid drawback of the prior art.
Accordingly, an orthopedic sole structure of this invention is adapted for use in a shoe to relieve pain and discomfort, and includes an insole made from a first polymeric material with a first stiffness, and an insert made from a second polymeric material with a second stiffness. The insole includes a metatarsals support portion, a tarsals support portion, and an intermediate arch support portion interposed therebetween. The insole defines an imaginary central line that extends from the metatarsals support portion toward the tarsals support portion. Each of the metatarsals and tarsals support portions has first upper and lower surfaces opposite to each other in a transverse direction relative to the central line. The intermediate arch support portion has left and right lateral edges extending between the metatarsals and tarsals support portions at opposite sides of the central line, and second upper and lower surfaces opposite to each other in the transverse direction. The second lower surface of the intermediate arch support portion has a recess which extends toward the second upper surface to terminate at a bottom, and which extends from the left lateral edge toward the right lateral edge beyond the central line, and which terminates at an abutment wall which joins with the bottom. The bottom has an inner bottom area adjacent to the abutment wall, an outer bottom area adjacent to the left lateral edge, a front bottom area adjacent to the metatarsals support portion and between the inner and outer bottom areas, and a rear bottom area adjacent to the tarsals support portion and between the inner and outer bottom areas. The insert has a configuration which complements with and which is insertable into the recess. The insert has third upper and lower surfaces opposite to each other in the transverse direction, and an inner abutment edge. The third upper surface has an inner surface area, an outer surface area, a front surface area, and a rear surface area such that when the insert is brought to be fitted in the recess to have the inner abutment edge abut against the abutment wall, the inner, outer, front and rear surface areas respectively mate with the inner, outer, front and rear bottom areas while the third lower surface of the insert is flush with the second lower surface of the intermediate arch support portion. The outer surface area is disposed at an elevation higher than the inner surface area relative to the third lower surface, thereby lifting the outer bottom area so as to permit resting of an intermediate arch portion of a user""s foot thereon.